1 package org.apache.turbine.modules.screens;
2
3 /* ====================================================================
4 * The Apache Software License, Version 1.1
5 *
6 * Copyright (c) 2001 The Apache Software Foundation. All rights
7 * reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
19 * distribution.
20 *
21 * 3. The end-user documentation included with the redistribution,
22 * if any, must include the following acknowledgment:
23 * "This product includes software developed by the
24 * Apache Software Foundation (http://www.apache.org/)."
25 * Alternately, this acknowledgment may appear in the software itself,
26 * if and wherever such third-party acknowledgments normally appear.
27 *
28 * 4. The names "Apache" and "Apache Software Foundation" and
29 * "Apache Turbine" must not be used to endorse or promote products
30 * derived from this software without prior written permission. For
31 * written permission, please contact apache@apache.org.
32 *
33 * 5. Products derived from this software may not be called "Apache",
34 * "Apache Turbine", nor may "Apache" appear in their name, without
35 * prior written permission of the Apache Software Foundation.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 * ====================================================================
50 *
51 * This software consists of voluntary contributions made by many
52 * individuals on behalf of the Apache Software Foundation. For more
53 * information on the Apache Software Foundation, please see
54 * <http://www.apache.org/>.
55 */
56
57 // Turbine stuff.
58 import org.apache.turbine.modules.Screen;
59 import org.apache.turbine.util.RunData;
60
61 // ECS Classes
62 import org.apache.ecs.ConcreteElement;
63
64
65 /***
66 * Base class for writing Screens that output binary data. This class
67 * is provided as a helper class for those who want to write Screens
68 * that output raw binary data. For example, it may be extended into
69 * a Screen that outputs a SVG file or a SWF (Flash Player format)
70 * movie. The only thing one has to do is to implement the two
71 * methods <code>getContentType(RunData data)</code> and
72 * <code>doOutput(RunData data)</code> (see below).
73 *
74 * <p> You migth want to take a look at the ImageServer screen class
75 * contained in the TDK.<br>
76 *
77 * @author <a href="mailto:rkoenig@chez.com">Regis Koenig</a>
78 * @version $Id: RawScreen.java,v 1.1.1.1 2001/08/16 05:08:37 jvanzyl Exp $
79 */
80 public abstract class RawScreen extends Screen
81 {
82 /***
83 * Build the Screen. This method actually makes a call to the
84 * doOutput() method in order to generate the Screen content.
85 *
86 * @param data Turbine information.
87 * @return A ConcreteElement.
88 * @exception Exception, a generic exception.
89 */
90 protected final ConcreteElement doBuild(RunData data)
91 throws Exception
92 {
93 data.getResponse().setContentType(getContentType(data));
94 data.declareDirectResponse();
95 doOutput(data);
96 return null;
97 }
98
99 /***
100 * Set the content type. This method should be overidden to
101 * actually set the real content-type header of the output.
102 *
103 * @param data Turbine information.
104 * @return A String with the content type.
105 */
106 protected abstract String getContentType(RunData data);
107
108 /***
109 * Actually output the dynamic content. The OutputStream can be
110 * accessed like this: <pre>OutputStream out =
111 * data.getResponse().getOutputStream();</pre>.
112 *
113 * @param data Turbine information.
114 * @exception Exception, a generic exception.
115 */
116 protected abstract void doOutput(RunData data)
117 throws Exception;
118
119 /***
120 * The layout must be set to null.
121 *
122 * @param data Turbine information.
123 * @return A null String.
124 */
125 public final String getLayout(RunData data)
126 {
127 return null;
128 }
129 }
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